Sadiron assembly



Feb. 15, 1949. w H, MCLELLAND ETVAL 2,461,561

sADIRoN ASSEMBLY 2 Sheets-Sheet l Filed May 17, 1944 FR3-Z rol 43 Feb. l5, 1949.

w. H. MCLELLAND ET A;

SADIRON ASSEMBLY 2 Sheets-Sheet 2 Filed Mary 17, 1944 e7 nos Patented Feb. 15, 1949 SADIRON ASSEMBLY William H. McLelland, Mansfield, Ohio, and Eric J. Ajax,

Minneapolis, Minn.,

assignors, by

mesne assignments, to Argus, Incorporated, Ann Arbor, Mich., a corporation of Michigan Application May 17, 1944, Serial No. 535,919

(Cl. 21S-25) 2 Claims. i

This invention relates to electric irons and more particularly to a sole plate, heater and pressure plate sub-assembly of such apparatus. In accordance with the usual construction of electric irons there is provided a sole plate of usual contour which is heated by an electric heating element. In order to provide for the uniform and pressure plate sub-assembly of an electric iron 1" wherein the heating element is maintained in uniform mechanical contact and in good heat conductive relation with the sole plate, throughout the life of the electric iron. It is a further object of the invention to provide a sole plate heater element and pressure plate assembly wherein the sole plate and pressure plate are of dissimilar materials having dissimilar coeicients of heat expansion, and in such an apparatus to provide an improved construction wherein the heating element is maintained under uniform pressure in mechanical contact with the sole plate It is a further object of the invention to provide a self-contained electric iron sub-assembly of sole plate, heating element and pres-sure plate and including in such an arrangement elements having dissimilar coefoients of heat expansion.

Other and further objects of the invention are those inherent in the apparatus hereinafter illustrated, described and claimed.

The invention i-s illustrated with reference to the drawings in which Figure 1 is a side elevational view of the eleotric iron of the invention;

Figure 2 is a side elevational View, portions of the iron being shown in section along the longitudinal center line of the iron;

Figure 3 is a fragmentary plan View of the center line portion of the sole plate taken in the direction of arrows 3-3 of Figure 2;

Figure 4 is a side view of the sole plate, heating element and pressure plate sub-assembly;

Figure 5 is a plan view of the sole plate heating element and pressure plate sub-assembly of Figure 4 Figure 6 is a cross sectional View of the pressure plate only, taken in the direction of arrows 5 5 of Figure 5;

Figure 7 is a vertical sectional view of the apparatus of Figure 5, taken in the direction of ar- "ows 'l-'.1 of Figure 5;

Figure 8 is a plan view of the sole plate and heating element, including the insulating foils and heating panels of said element, being illustrated oy dotted lines and ne lines; and

Figure 9 is a cross sectional view taken in the direction of arrows S-S of Figure 5.

Referring to the drawings, the electric iron of the present invention is illustrated in Figure 1 here generally designates the sole plate. Upon the sole plate there i-s mounted an outer shell E i provided with a decorative rib l2 for artisto and reinforcement purposes. Upon the shell l! there is mounted a shield plate I3 which serves, as hereinafter illustrated, as a mounting plate for the terminal block, signal lamp, and handle of the apparatus. superimposed upon and attached to the shield and to the Shell there is provided a handle generally designated l5 having a front support portion IB and a rear support portion Il attached to the base of the iron. The handle is provided with a front shield it' in which an indicator lamp lens 2G is mounted. The rear portion of the handle is provided with a tip 2l which with the skirt 22 mounted on the sole plate serves as a steady rest when the iron is tilted backwards. An electrical cord Z3 is connected to the rear post Il of the handle and upon the rear portion 25 of the shell there is mounted a control knob 25 for regulation oi the combined thermostatic control and on-and-oi switch of the iron.

The novel features of design and construction of the handle, shield, shell and thermostatic control together with other features of the upper iron construction form no part of the present invention, and reference is therefore only briefly made to them herein for explanatory purposes. Such novel features of the invention are claimed in our copending applications entitled Electric iron assembly, Ser. No. 535,920, Electric iron, Ser. No. 535,918, and design for Electric irons, Ser. lilo. Dll3,630, now Patent Des. 139,040, led of even date herewith.

Referring to Figure 2 the front portion I6 of the handle is cored out so as to provide a hollow space 223 which is open at the bottom 3Q when the handle is removed. Access may also be had to the interior space 28 by removal of the shield i8 which is fastened in place by the in-turned tip 'l and the retaining spring 32. The rear portion Il' of the handle is also provided with an interior open space 33 to which access may likewise be had through the open bottom 3d when the handle isv removed. The electrical-connection to the ironA extends l. through the right rear portion of the handle l5, as illustrated in Figures 1 and 2, wherein the electrical connection 23 is illustrated as entering the interior space 33 at opening The skirt 22 of the iron is fastened to the sole plate by a pair of screws 3l and the shell l l is fastened by a single large retaining screw 38 which extends through the shell intothe pressure plate generally designated fill, to be' described in greater detail hereinafter. The shield i3 is positioned between the handle andthe shell, the rear portion of the handle being fastened to the shell by a pair of screws ill, one at each side of the iron-extending,through-the shirt portionZE of the iron int-o the bosses i2 and 43 at the rear lateral portions` ci, the. baclc'handle support il', The front of handle bis attachedin place and hence assists in holding the shield i3 in place upon the shell l a' the .front attachment of the handle being by means of a. screw. It-which extends from the screw recess #le of the handle into a threaded opening 4l in the front portionv of the shell.

Access tothe screw t5 may be had when the u cover plate I8 is.v removed from the handle.

Referringto Figures v3Y through 9, there is illus trated a sole plate, heater padand pressure plate sub-assemblyof the iron.r As illustrated in these figures, the sole plate! ll-has a peripheral contour, as illustrated in Figure 8, being chamfered at the edge, as illustratedat 82 The sole plate is preferably of aluminum or aluminum alloy and may, if desired, be. chromium platedor otherwise plated for. decorative purposes, as well as to presenta smooth, mirror-like ironing surface. Upon thesole plate there is positioned a flat panel type electrical heating element assembly generally designated El), the outer contour of which is illustratedby. the dotted lines.v The heating element is composed of an upper andiower panel of electrical insulating material, preferably mica, having the contourV shown 'oy the dotted line 5i, Figure AEs. Twol such insulating panels are utilized and each is cut outinthe centenas. indicated by the dotted' line 52. Between thetop and bottom insulating. panels ofthe heating element there is positioned' another. panel 53 of insulating material, preferably mica', the contour of which is illustrated byV the dot. and dash lines, it being noted that this foil is2 cut away along the rear central portion so va'sto present at least a central area dened by the. lines A-.B, B-C, C-D, D"-E, E-F, lil-G', G-I-I, H-I, I-J., J-K, K-L, L-A. The panel E3 is alsopreferably cut away alongv the. lines U-V and X-Y, and a strip cut out fromS to T soas almost to divide the panel. ThisV is for convenience in winding the heater wire 55" onthe panel. However, it is to be emphasized that the area defined by the lines A-B through L-A is located centrally of the soleY plate and is relatively smallin area as compared to the total area of' the sole plate lil, The insulating foil 53 whichis preferably of thin mica serves asV an element on which the electrical heating wire is wound as indicated by the line 55. The electric resistance wire -55-extends from one terminal extension 5t. and thenis wound on the portion of panel whichis above the centerline, as shown in; Figure 8, and thenv extends across at 5l to Lin = fits in` a slot 85 in the sole plate.

the lower half of the panel 53 below a center line ci Figure 8, the contour of the two halves making panel all being indicated by the dot and dash line. The second terminal extension of the ater is indicated at 58. If desired, a third con. action may be brought out at 59 to serve as a connection to the pilotflamp'lll, It will thus be observed thatl the electric resistance. wire in the heating element neatly encompasses the central area defined by the lines A-B through L-A, heretofore defined.

The pressure plate generally designated 40 conof a thickened center land dll which extends fswise of the iron from the line El to the line 'Gutside oi this thickened center portion of thinner, as indicated at t3, but is reinby stiif'ening webs 55, E5, 6l, 58, it, 'il and extending outwardly from the thickened center land til and tapering down to the edge of the pressure plate, as illustrated in Figures 6, '7 and 9. The thickened center land, ll is slotted from the rear to about the middle, between the lines i3 and 74, the base of the pressure plate being entirely cut t rough between these lines i3 and le. As a resuit there are presented two symmetrical lands 85.3 Si extending backwardly from the front the rear end of the pressure plate terminating 82 and til. The pressure plate is shaped at lil-3l@ and also apertured at $5 for clearance purposes, as hereinafter indicated.

Referring to Figures 3, 4 and 8 the upper por tion of tie soleplate lil is milled out so as to present a slot 55, the ends of the slot being rounded at the end and deepened at 86 and 8l. In the slot thereis positioned a metal strip generally designated SS which is made up of two parts @il and 8l`separatedby a gap d2. The strip has a width and` thickness such that it neatly At the outer ends of the strip pieces @il and Sl' and to the bottom surface there are attached two circular wash ers S3 and 95 respectively, which are' preferably welded in place so as: to constitute a unitary part of the strips 9B and 9i, respectively. The washers 93 and 95 are of such size as'neatly to t into the depressions 5l and 3S respectively inthe sole plate. The extreme ends of the strips Si) and di are attached to the-sole plate by screws Q6 and 9i' respectively which are threaded into the sole plate, the endwisestrans on the Astrip being taken on the washers. The'two strips 99 and SI are of kmetal dissimilarv from the metal of the sole plate lll and such as to havea relatively much lower coefficient of expansion. The strips 99 and 8l may be made of steel, but are preferably made of Invar, whereas the sole plate is preferably made ofv aluminum or aluminum alloy and consequently has a much larger coeiiicient of expansion than the strip. The-gap92 `between the two strips ii and is bridged by a strip 93 which is bent upwardly in its middle portion it l, The two ends of the strip 98 are rivetedoiI otherwise fastened at m2 to the strips 90 and-Qlrespectively. The center portion I0 of thestrip QB is provided with an insulating button lil-Siwhichlextends through asmall hole itt in the center of the strip 93.

Accordingly where the sole plate has a greater pansion serves to control contacts generally designated |05 and opens and closes the circuit through the electrical heating element generally designated 50. The construction of the contacts |95 and their control arrangements generally indicated at |06 constitutes the subject matter of my copending application entitled Electric iron, Ser. No. 535,918, led of even date herewith and will not be further described herein except to state that by operation of the knob 26, contacts |05 may be controlled so as entirely to disconnect the heater element 50 from the electrical cord 23 or by other suitable adjustment the contacts 105 can be caused to open and close so as to maintain any desired operating temperature at the sole plate l0.

The pressure plate 40 is preferably made of iron and hence has a different coefficient of expansion than the sole plate I0 which is preferably made of aluminum or aluminum alloy, and as a result a certain creepage occurs between the pressure plate and the sole plate due to variations in temperature of the unit. The attachu ment oi' the pressure plate 40 to the sole plate is accomplished by a plurality of screws, four screws 101, |08, |09 and H0 being shown in the illustrated embodiments. The screws IGT-l l0 all pass through the central area defined by the lines A-B through L-A, heretofore described, and since this area is relatively small as compared to the total dimensions of the sole plate and pressure plate, the amount of creepage between the screws is minimized. The holes in the pressure plate through which the screws lOl-i le pass are of a size such as to provide slight clearance such as illustrated at H0 and |08 in Figure '7.

In fabricating the sub-assembly shown in Figures 3 through 9, the thermostat control switch 80 is placed on the sole plate and is fastened by means of screws 96 and 91, and the heating element 50 is then located on the sole plate with the central aperture 52 through the heating element insulating foils located so that the center bent strip 98 of the control 80 extends upwardly therethrough. The pressure plate, which is coextensive in outer peripheral dimension with the heating element assembly 50, is then placed upon the heating element and the screws l 08-l I 0 inserted and pulled down tightly. As a result the heating element 50 is tightly clamped between the pressure plate 40 and the sole plate I 0.

Thereafter, during operation of the iron the sole plate and pressure plate are heated to varying temperatures, and being of dissimilar metals creepage occurs between adjacent portions of the pressure plate and sole plate. Throughout the relatively small central area dened by the lines A-B through L-A, heretofore described, the creepage is relatively small due to the smallness of the area involved, but at the extreme edges of the pressure plate a relatively large oreepage occurs. However, due to the central attachment of the pressure plate to the sole plate .by means of screws lill-H0 the creepage does not have any loosening effect, and as a resultthe heating element 50 is maintained in tightly clamped relationship throughout the life of the iron.

It is obvious that less than four screws or more than four screws may be utilized for the attachment of the sole plate to the pressure plate or attachment means such as rivets or other mechanical fastening devices may be utilized, provided however that the area in which such attachment of the pressure plate and sole plate is (ifi made is kept at a minimum and located in the central portion of the pressure plate and sole plate. When this is done the heating element is maintained in uniform tightly clamped relationship throughout the life of the iron.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specic embodiments herein except as defined by the appended claims.

What we claim is:

1. An electric iron sub-assembly comprising a sole plate, a insulated electric heating element positioned on and overlying the sole plate, a pressure plate overlying the heating element, said pressure plate comprising a relatively thin flat base portion having an elongated narrow longitudinal aperture through the center portion thereof, said pressure piate having heavy walls integral with the base portion immediately adjacent each side of said longitudinal aperture, stiffening webs integral with the walls and base portion extending radially from the walls to the edges of the thin iiat base portion, fastening means extending downwardly through the walls into the sole plate near the central portion of said sole plate for holding the pressure plate in ciamping relation on the heating element, and a thermostatic element and switch contacts operated thereby located between said walls in alignment with said aperture.

2. An electric iron sub-assembly comprising a sole plate, a flat, insulated electric heating element positioned on and overlying the sole plate, a pressure plate overlying the heating element, said pressure plate comprising a relatively thin flat base portion having an elongated narrow longitudinal aperture through the center portion thereof, said pressure plate having a heavy continuous upstanding wall extending along each side of the said longitudinal aperture and around the front thereof and stiffening webs integral with the wall, and base portion extending radially from the walls to the edges of the thin fiat base portion, fastening means extending downwardly through the walls into the sole plate near the central portion of said sole plate for holding the pressure plate in clamping relation on the heating element, and a thermostatic element and switch contacts operated thereby between said walls in alignment with said aperture.

WILLIAM H. MCLELLAND. ERIC J. AJAX.

REFERENCES CITED The following references are of record in the file of this patent:

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